自托管Windows GitHub Action Runner无法更新GITHUB_PATH问题

使用以下GitHub Actions工作流时，在官方Windows Runner上运行正常，但在基于Windows Server 2022核心版自定义镜像搭建的自托管Runner（版本2.303.0，系统为Windows Server 2022数据中心版）上执行失败：

name: Test set path
on:
  workflow_dispatch:
jobs:
  test-cross-aws:
    runs-on: [self-hosted, '${{ matrix.platform.os }}', x64, '${{ matrix.platform.label }}']
    #runs-on: windows-latest   
    strategy:
      matrix:
        platform: [{ os: windows, label: wix-aws-windows-test }]
    steps:
      - name: create fake batchfile
        if: always()
        run: |
           mkdir testfolder
           echo "@echo off" | Out-File -FilePath testfolder/testbatch.bat -Encoding utf8
           echo "echo SOMETHING" | Out-File -FilePath testfolder/testbatch.bat -Encoding utf8           

      - name: add path
        if: always()
        run: echo "$pwd\testfolder;" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append

      - name: run custom binary with path
        if: always()
        run: testbatch.bat

报错信息：

testbatch.bat : The term 'testbatch.bat' is not recognized as the name of a cmdlet, function, script file, or operable 
program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
At C:\actions-runner\_work\_temp\744d9b45-8f99-4db5-ba7d-b95aad4dde97.ps1:2 char:1
+ testbatch.bat
+ ~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (testbatch.bat:String) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : CommandNotFoundException
 
Error: Process completed with exit code 1.

针对自托管Windows Runner上的这个问题，可以尝试以下几种修复方式：

1. 显式通过CMD运行批处理文件 #

PowerShell环境下直接调用.bat文件会优先查找cmdlet而非可执行文件，显式调用CMD执行批处理可绕过该逻辑：

- name: run custom binary with path
  if: always()
  run: cmd /c testbatch.bat

2. 用可靠方式添加路径到GITHUB_PATH #

手动拼接路径易出现格式问题，改用Join-Path构造路径，并用Add-Content追加内容（比Out-File -Append更稳定），同时用$env:GITHUB_WORKSPACE替代$pwd确保路径指向正确工作目录：

- name: add path
  if: always()
  run: |
    $targetPath = Join-Path -Path $env:GITHUB_WORKSPACE -ChildPath "testfolder"
    Add-Content -Path $env:GITHUB_PATH -Value $targetPath -Encoding utf8

3. 验证并修复PATHEXT环境变量 #

Windows的PATHEXT变量决定系统识别的可执行文件扩展名，若自托管Runner的PATHEXT缺失.BAT，即使路径正确也无法直接运行批处理。先检查变量：

- name: Check PATHEXT
  run: Write-Output $env:PATHEXT

若缺少.BAT，可在工作流中追加该扩展名：

- name: Add .BAT to PATHEXT
  run: |
    $updatedPathext = "$env:PATHEXT;.BAT"
    echo "PATHEXT=$updatedPathext" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append

4. 验证路径是否正确添加 #

在添加路径后增加步骤，确认目标目录已加入系统PATH：

- name: Verify PATH includes testfolder
  run: Write-Output $env:PATH | Select-String -Pattern "testfolder"

内容的提问来源于stack exchange，提问作者AlexS